which ones look lyke what between your older Colts vs your newer Colts, do you happen to have an SP-1 in original condition ? i have one but someone replaced the bolt & carrier during it's lyfetyme, it now has a new notched F.A. carrier, my oldest all original Colt was made in 1985 & the "P" is on the last leg of the "M" & the "C" has a slight space between it & the "P" & the entire MPC is very clear & obvious, that is why i started this note, because the other bolts have the same scheme, but are barely visible, one of my NIBs is clearly visible......